Thick mud engulfed Mary Alvarez's white rubber boots as she took her first steps through the swamplands of Aransas National Wildlife Refuge.

"This is the first time I've come out after a big rain," Alvarez said. "I sunk down to the bottom and had to be helped out."

For Alvarez, a resident of Rockport, it was her second year picking up trash as a volunteer on National Estuaries Day.

Guided by Capt. Tommy Moore, owner of Rockport Birding and Kayak Adventures, a group of 12 volunteers set out on Moore's boat, The Skimmer, to clean the coastline for the upcoming arrival of the whooping cranes.

Colleen McCue, volunteer coordinator for the Mission-Aransas National Estuarine Research Reserve, oversaw the cleanup for the endangered birds. "They're coming from Wood Buffalo National Wildlife Refuge in Canada," McCue said, "They migrate down and spend the winters here in Rockport."

At the end of the day, McCue's group had cleared about 650 pounds of garbage from the coast, which was later picked up by other volunteers from the San Antonio Bay Foundation.

"It always feels good to clean up any environment," McCue said, "but when you know it's having an impact on an endangered species with less than 300 individuals, you really feel like you're doing something."